As is known, many implants, prostheses or endoprostheses are produced of polyether ether ketone (PEEK). Compared to metallic materials, this material has the advantage that the Elastic modulus of PEEK corresponds more to the Elastic modulus of cortical bones than metallic materials could ever achieve. Moreover, PEEK is permeable to X-rays, as a result of which the physician can observe bone integration of, for example, vertebral cages by means of corresponding radiograms during follow-up treatment. This would not be possible with a titanium cage.
However, for some time, implants and the like which are produced of PEEK have become subject to criticism. It could be observed that the human or animal bone does not completely adhere to the implant and grow into the implant, respectively. The bones rather form a seam on the surface of the PEEK material. In case that such a seam formation can be discovered on an X-ray image, this means that bone adhesion has not happened and that there is no sufficient stability regarding the inserted implant.
As a result of this, the implant either has to be removed and be replaced by a new one, or the implant has to be firmly fixed to the bone by means of other surgical methods. Another surgery is associated with additional stress, pain, and corresponding surgical risks for the patient.
Metallic material, particularly titanium, fulfills optimal conditions regarding growth into animal or human bone structures. It is proven that the bones adhere to the titanium, and, provided that the surface is accordingly designed, the bone can also grow into the microstructures of titanium materials.
Thus for a long time, there have been attempts to develop coatings and implant materials, respectively, such that, on the one hand, an improved bioactive surface layer and a related grow-into ability for animal or human bones is achieved, and, on the other hand, good Elastic moduli, as already realized through the usage of PEEK materials, can be obtained.
In EP 1372749 B1, a bioactive surface layer for implants and prostheses is disclosed, wherein the implant can consist of PEEK. A variable part of the surface layer consists of calcium phosphate phases, wherein the CA-ions and PO4-ions embedded in the surface layer are completely spread over a metal oxide layer. The metal oxide is titanium oxide, for instance. Furthermore, an additional coating of the surface layer with hydroxylapatite is described. Such hydroxylapatite coatings of implants are common methods to ensure improved growth of bone structures into the implant.
However, tests of the tensile strength values to be achieved and of the shearing forces to be resisted of common implants have fueled the desire for improved implants regarding the two values, but wherein the implants should also grow into animal or human bone structures in such a good manner, as is the case with an implant coating with hydroxylapatite, for instance.
Due to the aforementioned, the task of the embodiments presented here therefore is to provide an improved implant and method, comprising a coating which can be realized cost-efficiently, has improved tensile strength values, and which can be loaded with higher shearing forces. Furthermore, a method is provided, with the help of which a quick and cost-efficient production of a coated implant can be realized.